path: root/qdeclarativegesturearea.cpp

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#include "qdeclarativegesturearea_p.h"

#include <qdeclarativeexpression.h>
#include <qdeclarativecontext.h>
#include <qdeclarativeinfo.h>

#include <QtCore/qdebug.h>
#include <QtCore/qstringlist.h>

#include <QtGui/qevent.h>
#include <QtGui/qgesture.h>

#include "qdeclarativegesturehandler_p.h"
#include "gestureareaplugin_p.h"

#ifndef QT_NO_GESTURES

QT_BEGIN_NAMESPACE

// remove me and search-n-replace GESTUREHANDLER_D to Q_D
// when put this plugin back to the Qt source tree
#define GESTUREHANDLER_D(x) x##Private *d = d_ptr

class QDeclarativeGestureAreaPrivate
{
public:
    QDeclarativeGestureAreaPrivate(QDeclarativeGestureArea *q) : q_ptr(q), defaultHandler(0) { }

    QDeclarativeGestureArea *q_ptr;

    QList<QObject *> handlers;
    QObject *defaultHandler;

    static void handlers_append(QDeclarativeListProperty<QObject> *prop, QObject *handler) {
        QDeclarativeGestureAreaPrivate *d = static_cast<QDeclarativeGestureAreaPrivate *>(prop->data);
        QDeclarativeGestureArea *q = d->q_ptr;
        int type = handler->property("gestureType").toInt();
        // check that all needed properties exist
        if (!handler->property("gestureType").isValid() || !handler->property("gesture").isValid()
                || !handler->property("onStarted").isValid() || !handler->property("onUpdated").isValid()
                || !handler->property("onCanceled").isValid() || !handler->property("onFinished").isValid()) {
            qmlInfo(handler) << "Invalid GestureArea handler.\n"
                             << "A GestureArea handler should provide the following properties: "
                                "'gestureType', 'onStarted', 'onUpdated', 'onCanceled', 'onFinished' and 'gesture'";
            return;
        }
        Qt::GestureType gestureType = Qt::GestureType(type);
        // see if there is already a handler for that gesture type
        foreach(QObject *handler, d->handlers) {
            Qt::GestureType type(Qt::GestureType(handler->property("gestureType").toInt()));
            if (type == gestureType) {
                qmlInfo(handler) << "Duplicate gesture found, ignoring.";
                return;
            }
        }
        d->handlers.append(handler);
        if (GestureAreaQmlPlugin::self)
            GestureAreaQmlPlugin::self->allGestures << gestureType;
        if (type == 0 && GestureAreaQmlPlugin::self) {
            d->defaultHandler = handler;
            GestureAreaQmlPlugin::self->allDefaultAreas << QWeakPointer<QDeclarativeGestureArea>(q);
            foreach (Qt::GestureType gestureType, GestureAreaQmlPlugin::self->allGestures) {
                foreach (QWeakPointer<QDeclarativeGestureArea> area, GestureAreaQmlPlugin::self->allDefaultAreas) {
                    if (area)
                        area.data()->grabGesture(gestureType);
                }
            }
        } else {
            q->grabGesture(gestureType);
        }
    }
    static void handlers_clear(QDeclarativeListProperty<QObject> *prop) {
        QDeclarativeGestureAreaPrivate *d = static_cast<QDeclarativeGestureAreaPrivate *>(prop->data);
        d->handlers.clear();
    }
    static int handlers_count(QDeclarativeListProperty<QObject> *prop) {
        QDeclarativeGestureAreaPrivate *d = static_cast<QDeclarativeGestureAreaPrivate *>(prop->data);
        return d->handlers.count();
    }
    static QObject *handlers_at(QDeclarativeListProperty<QObject> *prop, int index) {
        QDeclarativeGestureAreaPrivate *d = static_cast<QDeclarativeGestureAreaPrivate *>(prop->data);
        return d->handlers.at(index);
    }

    void evaluate(QGestureEvent *event, QGesture *gesture, QObject *handler);
    bool gestureEvent(QGestureEvent *event);
};

/*!
    \qmlclass GestureArea QDeclarativeGestureArea
    \ingroup qml-basic-interaction-elements

    \brief The GestureArea item enables simple gesture handling.
    \inherits Item

    A GestureArea is like a MouseArea, but it has signals for gesture events.

    \e {Elements in the Qt.labs module are not guaranteed to remain compatible
    in future versions.}

    \qml
    import Qt.labs.gestures 0.1

    GestureArea {
        anchors.fill: parent

        Pan {
            when: Math.abs(gesture.delta.y) < Math.abs(gesture.delta.x)
            onUpdated: {
                // use gesture.delta
            }
        }
        TapAndHold {
            onFinished: {
                // do something
            }
        }
    }
    \endqml

    Each gesture object has a \e when clause that will be evaluated on start of the
    gesture. If the when clause evaluates to true the gesture is accepted and the
    \e onStarted script is handled.  If there is no \e when clause then it will
    automatically be accepted.  Notice that a gesture that is not accepted will be
    offered to another gesture area that is also covering the area where the gesture
    happened.

    After acceptance of a gesture updates in movement call \e unOpdated and finally either
    the script from \e onCanceled or \e onFinished is handled when the gesture is canceled
    or finished.
    Each gesture object has a \e gesture parameter that has the properties of the gesture
    which can be used in all of the script properties.

    The full list of supported gesture-types handled by a GestureArea is listed in the table
    below.
    \table
    \header \o Type \o Description
    \row \o Pan \o a movement of pressing and holding while moving the pointing device on the gesture area
    \row \o Tap \o a touch and release without moving
    \row \o TapAndHold \o a touch without releasing or moving for a longer time
    \row \o Pinch \o is used to handle the moving using more than one finger
    \endtable

    GestureArea is an invisible item: it is never painted.

    \sa MouseArea, {declarative/touchinteraction/gestures}{Gestures example}
*/

/*!
    \internal
    \class QDeclarativeGestureArea
    \brief The QDeclarativeGestureArea class provides simple gesture handling.

*/
QDeclarativeGestureArea::QDeclarativeGestureArea(QDeclarativeItem *parent) :
    QDeclarativeItem(parent)
{
    d_ptr = new QDeclarativeGestureAreaPrivate(this);
    setAcceptedMouseButtons(Qt::LeftButton);
    setAcceptTouchEvents(true);
}

QDeclarativeGestureArea::~QDeclarativeGestureArea()
{
    delete d_ptr; d_ptr = 0;
}

QDeclarativeListProperty<QObject> QDeclarativeGestureArea::handlers()
{
    GESTUREHANDLER_D(QDeclarativeGestureArea);
    return QDeclarativeListProperty<QObject>(this, d, QDeclarativeGestureAreaPrivate::handlers_append,
                                             QDeclarativeGestureAreaPrivate::handlers_count, QDeclarativeGestureAreaPrivate::handlers_at,
                                             QDeclarativeGestureAreaPrivate::handlers_clear);
}

bool QDeclarativeGestureArea::sceneEvent(QEvent *event)
{
    GESTUREHANDLER_D(QDeclarativeGestureArea);
    switch (event->type()) {
    case QEvent::GraphicsSceneMousePress:
    case QEvent::MouseButtonPress:
    case QEvent::TouchBegin:
        event->accept();
        return true;
    case QEvent::Gesture:
        return d->gestureEvent(static_cast<QGestureEvent *>(event));
    default:
        break;
    }
    return QDeclarativeItem::sceneEvent(event);
}

void QDeclarativeGestureAreaPrivate::evaluate(QGestureEvent *event, QGesture *gesture, QObject *handler)
{
    handler->setProperty("gesture", QVariant::fromValue<QObject *>(gesture));
    QDeclarativeScriptString when = handler->property("when").value<QDeclarativeScriptString>();
    if (!when.script().isEmpty()) {
        QDeclarativeExpression expr(when.context(), when.scopeObject(), when.script());
        QVariant result = expr.evaluate();
        if (expr.hasError()) {
            qmlInfo(q_ptr) << expr.error();
            return;
        }
        if (!result.toBool())
            return;
    }

    // those names map to the enum Qt::GestureState
    static const char * scriptPropertyNames[] = { "0", "onStarted", "onUpdated", "onFinished", "onCanceled", "__ERROR" };
    QDeclarativeScriptString script = handler->property(scriptPropertyNames[gesture->state()]).value<QDeclarativeScriptString>();
    if (!script.script().isEmpty()) {
        QDeclarativeExpression expr(script.context(), script.scopeObject(), script.script());
        expr.evaluate();
        if (expr.hasError())
            qmlInfo(q_ptr) << expr.error();
    }
    event->accept(gesture);
    handler->setProperty("gesture", QVariant());
}

bool QDeclarativeGestureAreaPrivate::gestureEvent(QGestureEvent *event)
{
    if (handlers.isEmpty())
        return false;

    event->accept();

    QList<Qt::GestureType> handlersTypes;
    foreach(QObject *handler, handlers) {
        Qt::GestureType type(Qt::GestureType(handler->property("gestureType").toInt()));
        handlersTypes.append(type);
        event->ignore(type);
    }

    QSet<Qt::GestureType> handledGestures;
    for (int i = handlers.size()-1; i >= 0; --i) {
        Qt::GestureType gestureType = handlersTypes.at(i);
        if (!gestureType)
            continue;
        if (QGesture *gesture = event->gesture(gestureType)) {
            handledGestures << gestureType;
            QObject *handler = handlers.at(i);
            evaluate(event, gesture, handler);
        }
    }

    if (defaultHandler) {
        // filter all gestures through the default handler
        foreach (QGesture *gesture, event->gestures()) {
            if (!handledGestures.contains(gesture->gestureType()))
                evaluate(event, gesture, defaultHandler);
        }
    }
    return false;
}

QT_END_NAMESPACE

#endif // QT_NO_GESTURES